For bonding glass substrates with an adhesive, in particular with an adhesive tape, the glass surface is typically pretreated in order to enhance the bond strength of the adhesive. This is achieved by the application of a primer prior to the application of the adhesive tape. Such a two-step procedure is recited for example in US 2005/0081993 A1 (Ilkka et al.), in which a silane primer is used to prepare the glass surface. In the following step, an acrylic PSA-tape is applied to the pretreated surface, whereas the adhesive tape may be a dual-layer film. Another possibility is to pre-treat the surface of the PSA-tape before application to the glass surface. Alternatively, the silane may be incorporated into the adhesive layer of the film by mixing it into the PSA formulation.
In EP 0 889 106 A1 (Johnson et al.), a single layer adhesive film is recited, which is obtained by photopolymerization of a monomeric mixture comprising an acrylic ester and an epoxy resin, whereas the composition may further comprise an organofunctional silane.
A single layer film may however not satisfy the bonding requirements for different substrates, which is however often required for bonding solar panels, which have typically a glass backside. In addition, the silane impregnated tapes recited in the documents mentioned above show a limited shelf-life. In addition, the bond strength to glass surfaces may strongly decrease over time under environmental influence, in particular humidity which may finally lead to a bond break.